Alcoholics have an increased incidence of pulmonary diseases that are in part due to altered lung host defense functions related to alcohol toxicity. There is also a strong tendency for alcoholics to smoke heavily. A major airway defense function that is impaired during both alcohol ingestion and cigarette smoking is the mucociliary clearance system which is dependent on the coordinated beating of cilia that line the airways. One possible mechanism of mucociliary impairment common to both alcohol ingestion and smoking is acetaldehyde exposure since acetaldehyde is produced during the metabolism of ethanol, both by the liver and locally in the airways, and is also found in significant amounts in the vapor phase of cigarette smoke. Recent studies from our lab indicate that ethanol stimulates ciliary motility through a nitric-oxide dependent mechanism. Additional findings indicate that this NO-dependent mechanism is especially sensitive acetaldehyde injury. In this context we hypothesize that: ETHANOL AND ACETALDEHDYE ALTER NO-DEPENDENT CILIARY MOTILITY IN AIRWAY EPITHELIA. To test this hypothesis we will perform experiments focused around four specific aims: 1) Characterize the effects of ethanol on airway epithelial NO synthases (NOS) and correlate NOS activation with ethanol-induced ciliary motility changes; 2) Determine how ethanol stimulates the ciliary motility signal transduction pathway by evaluating sequential steps in the cilia activation pathway; 3) Confirm and characterize the effects of acetaldehyde on NO-dependent changes in ciliary motility; 4) Determine the mechanisms(s) by which acetaldehyde impairs NO-dependent stimulation of ciliary motility. The impact of alcohol and smoking-related respiratory illnesses on society is immense. The studies we have outlined in this proposal will explore a novel NO-dependent mechanism by which ethanol and acetaldehyde enhance or impair ciliary function, respectively. Establishing both the mechanisms by which ethanol appears to stimulate and acetaldehyde impairs ciliary function in airways cells will provide meaningful insight into the roles alcohol ingestion and smoking play in the pathogenesis of bronchitis, pneumonia and lung cancer.